Technical Field
The present disclosure relates to a control technology which is applied to an internal combustion engine including an exhaust turbine supercharger (turbocharger) for driving a centrifugal type compressor by using exhaust gas energy, and in particular to a technology to control a waste gate valve attached to the turbocharger.
Description of Background Art
As a supercharger applied to an internal combustion engine, there has been known a turbocharger which is provided with a turbine arranged in an exhaust passage, a compressor arranged in an intake passage, a bypass passage for causing exhaust gas to flow therethrough while bypassing the turbine, and a waste gate valve equipped with a valve body for opening and closing the bypass passage.
A first patent literature discloses an arrangement of an internal combustion engine in which an exhaust gas purification catalyst is arranged in an exhaust passage at a location downstream of a turbine of a turbocharger, wherein when the degree of opening of a valve body of a waste gate valve is equal to or larger than a predetermined degree of opening, most of the exhaust gas having flowed out from an outlet of a bypass passage impinges directly against an upstream side end face of the exhaust gas purification catalyst, whereas when the degree of opening of the valve body of the waste gate valve is less than the predetermined degree of opening, most of the exhaust gas having passed through the bypass passage impinges directly against a wall surface of the exhaust passage which is located upstream of the upstream side end face of the exhaust gas purification catalyst. In addition, in the first patent literature, there is also disclosed a method in which in cases where warming of the exhaust gas purification catalyst is required, as when the internal combustion engine is cold started, exhaust gas of high temperature is caused to impinge directly against the exhaust gas purification catalyst, by controlling the degree of opening of the valve body of the waste gate valve to a degree of opening equal to or larger than the predetermined degree of opening. Moreover, in the first patent literature, there is also disclosed a method in which in cases where the temperature of the exhaust gas purification catalyst may rise to an excessive extent, as when the internal combustion engine is operated at a high load, exhaust gas of high temperature is caused not to impinge directly against the exhaust gas purification catalyst, by controlling the degree of opening of the valve body of the waste gate valve to a degree of opening smaller than the predetermined degree of opening.
In a second patent literature, there is disclosed a technology in which when processing to stop combustion of fuel (fuel cut off processing) is carried out by stopping the supply of fuel to an internal combustion engine in the course of the operation of the internal combustion engine, a valve body of a waste gate valve is fully closed.